This invention relates to lens protectors and more particularly to method and apparatus for inhibiting high velocity particulate contaminants in the atmosphere contacting the lens surface in a laser machine such as a scriber.
Laser beams are used in numerous operations such as machining, drilling, cutting cloth, and scribing grid lines in the surface of thin ceramic plates on which a plurality of hybrid circuits are formed prior to the plate being separated into individual substrates and circuits. During the scribing of a ceramic plate that moves in a grid pattern under a laser beam, for example, ceramic dust and minute ceramic particles that are torn from the plate by the laser beam fan out in a rooster tail that moves upward in a direction generally the same as that of movement of the ceramic plate and toward the surface of a lens in the laser. These flying particles may have sufficient velocity to pit the lens surface if they are allowed to strike it. With sufficient pitting, the lens no longer focuses the laser beam. In a prior-art laser scriber machine, two tubes are supported proximate the lens surface so as to blow air at right angles to the lens axis and into the mouth of a vacuum hose. This produces an air lock door between the lens and a ceramic plate that is being scribed. Unfortunately, this technique is ineffective for blocking the passage of ceramic particles when a ceramic plate is moved in more than one direction in a common plane during a scribing operation. In a laser system using this technique, it was found necessary to disassemble the equipment and clean the lens a number of times each day. It was also necessary to replace the lens a number of times each week. An object of this invention is the provision of improved method and apparatus for protecting the lens in a laser machine by discouraging particulate contaminant in the atmosphere from contacting the lens surface.